CAS-Climate: EAGER – Preventing Pore Clogging by Aggregated Carbohydrate Nanocrystals during CO2 Sequestration in Deep Saline Aquifers

需要多种技术来解决气候危机，地下二氧化碳储存预计将成为一个必要的贡献者，全球二氧化碳储存能力估计为2，000 Gt。在二氧化碳长期储存安全性方面仍存在一些关切，以限制向大气或地下水系统的泄漏。封存的CO2可以通过断层、裂缝和有缺陷的井封渗漏;因此，大量的研究致力于泄漏监测和CO2羽流建模。一旦检测到泄漏，补救方法包括注入关闭、液压管理、去除注入的CO2、生物活性屏障和密封剂或其他物理屏障。然而，这些方法的实施增加了储存成本，导致CO2容量降低，并且经常导致注入地点的关闭。该项目旨在通过将温室气体捕获在稳定的泡沫中以防止泄漏来提高二氧化碳储存安全性。这种方法从未在高盐度盐水中实现过，主要是由于聚集的纳米颗粒过度堵塞岩石孔隙，导致各种问题，包括有限的CO2泡沫输送、储层中的压力累积、压降增加和容量降低。该项目的假设是，具有对CO2具有高亲和力的官能团的碳水化合物纳米晶体将吸附到气体/盐水界面上以防止孔隙堵塞，从而增强通过储集岩的CO2运输。为了支持这一假设，该项目有以下具体目标：（1）通过用耐热和耐化学性官能团修饰碳水化合物纳米晶体的表面来控制其亲CO2性;（2）通过增强CO2/CO2吸附防止砂岩岩心孔隙堵塞。该项目旨在建立在不使用任何表面活性剂的情况下成功地将二氧化碳隔离在地下的稳定泡沫中所需的基本知识。它还试图创造具有足够的热稳定性和化学稳定性的碳水化合物纳米晶体，以承受恶劣的地下条件。碳水化合物表面化学对CO2泡沫和二氧化碳运输的影响将在模拟深层盐水层的环境中进行测试。据推测，在CO2/盐水界面的改性纳米晶体的吸附将增强其通过多孔岩石的运输，这代表了一种新的方法，用于控制纳米颗粒通过多孔介质的运输。这项研究的成功可能会提高地质场地安全捕获二氧化碳的能力，同时填补纳米颗粒稳定泡沫这一相对较新的研究领域的知识空白。该项目的成功可能会在德克萨斯州和全国各地的深层盐水含水层附近创造私人投资机会。美国的林业（纤维素）和海洋食品（甲壳素）工业也可以通过扩大其潜在市场而受益于这一研究计划的成功。符合德克萨斯州基本知识和技能（TEKS）规定的教育标准的可持续发展活动将为中学生创建。该奖项反映了NSF的法定使命，并通过使用基金会的智力价值和更广泛的影响审查标准进行评估，被认为值得支持。

Multiple technologies are needed to solve the climate crisis, and underground CO2 storage, with an estimated global capacity of 2,000 Gt CO2, is expected to be a required contributor. Several concerns remain regarding long-term CO2 storage security to limit leakage to the atmosphere or groundwater systems. Sequestered CO2 can seep through faults, fractures, and defective well seals; thus, a significant amount of research has been dedicated to leak monitoring, and modeling of CO2 plume flows. Once a leak is detected, remediation methods include injection shut-off, hydraulic pressure management, removal of injected CO2, biologically active barriers, and sealants or other physical barriers. However, implementation of these methods increases the cost of storage, leads to reduced CO2 capacity, and often results in closure of the injection site. This project seeks to enhance CO2 storage security by trapping the greenhouse gas in a nanocrystal stabilized foam to prevent leakage. Such an approach has never been accomplished in high salinity brines, mostly due to the excessive clogging of rock pores by aggregated nanoparticles that lead to a variety of problems including limited CO2 foam transport, pressure buildup in the reservoir, increased pressure drops, and reduced capacity. The hypothesis of this project is that carbohydrate nanocrystals with functional groups possessing high affinity towards CO2 will adsorb onto the gas/brine interface to prevent pore clogging, thus enhancing nanocrystal transport through reservoir rocks. To support this hypothesis, the project has the following specific objectives: (1) To control the CO2-philicity of carbohydrate nanocrystals by modifying their surface with thermally and chemically resistant functional groups; (2) To prevent pore clogging of sandstone rock cores by enhancing nanocrystal adsorption onto CO2/brine interfaces.The project intends to establish fundamental knowledge required to successfully sequester carbon dioxide underground in a stable foam without using any surfactants. It also seeks to create carbohydrate nanocrystals bearing CO2-philic and hydrophilic groups with adequate thermal and chemical stability to withstand harsh underground conditions. The effect of carbohydrate nanocrystal surface chemistry on CO2 foam and nanocrystal transport will be tested in environments mimicking deep saline aquifers. It is hypothesized that adsorption of the modified nanocrystals at the CO2/brine interface will enhance their transport through porous rocks; this represents a new approach for controlling nanoparticle transport through porous media. Success of this research potentially will enhance the ability of a geological site to safely trap CO2, while filling knowledge gaps in the relatively new research field of nanoparticle stabilized foams. Success on this project may create private investment opportunities in Texas and across the nation near deep saline aquifers. The forestry (cellulose) and sea food (chitin) industries of the United States could also benefit from success of this research program by expanding their potential markets. A sustainability activity that meets the education standards specified in the Texas Essential Knowledge and Skills (TEKS) will be created for middle school students.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.